A Washington lobbyist once told me that the first rule of rainmakers is: "If it starts to rain, dance!"

In other words, if you're hired to get something done, by all means take credit for it if it happens, even if you had nothing to do with it.

Another version of the same principle is Ferris Buellerism. In the movie "Ferris Bueller's Day Off," the precocious teen sees a parade in downtown Chicago and proceeds to run in front of it as if he'd been leading it all along.

Fired White House aide Steve Bannon is a quintessential Ferris Bueller. My late friend Andrew Breitbart created the media empire that regrettably still bears his name. When he died, Bannon took over the parade Andrew launched.

Bannon followed the same playbook in the 2016 presidential race. He boarded the Trump train late and pretended he'd been the conductor all along. As Trump himself put it: "I like Steve, but you have to remember he was not involved in my campaign until very late. I had already beaten all the senators and all the governors, and I didn't know Steve. I'm my own strategist, and it wasn't like I was going to change strategies because I was facing crooked Hillary."

In the recent Alabama GOP runoff for U.S. Senate, Trump and Senate Majority leader Mitch McConnell supported incumbent Sen. Luther Strange, whose weakness as a candidate could be attributed to his near-total lack of charisma and the dodgy circumstances of his appointment to fill Attorney General Jeff Sessions' former Senate seat. (As Alabama's attorney general, Strange pushed to delay the impeachment of the governor, creating the appearance of a backroom deal.)

Strange's opponent in the runoff was former Alabama Supreme Court Justice Roy Moore, a well-known and controversial figure in the state. Moore was always way ahead in the polls. But Bannon parachuted into the state and backed the likely winner, insisting that a vote for Moore was a vote for Trump's agenda and would serve as a thumb in the eye of the Washington establishment, particularly McConnell. Moore won, and rainmaker Bannon danced, taking credit for something that would have happened anyway.

Now, Bannon is claiming he will back candidates to challenge every incumbent senator up for re-election in 2018, save for Ted Cruz, who is supported by the billionaire Mercer family, patrons of Bannon and Breitbart News.

It's understandable that Bannon and his employees at Breitbart would want to perpetuate the myth of Bannon's rainmaking skills. They're in the business of monetizing anger at Washington and the GOP "establishment." Less forgivable, if not necessarily less understandable, is the eagerness of the political press to perpetuate the myth that Bannon is a master political strategist and a kingmaker in Republican politics.

In 2016, at the height of Trump's popularity with grassroots Republicans, Breitbart tried his "fight the establishment" shtick and failed miserably. He backed Trump copycat Paul Nehlen's bid to topple House Speaker Paul Ryan in the Wisconsin GOP primary. Nehlen lost by 68 percentage points. Bannon tried the same thing in Senate primaries in Alabama, Arizona and Indiana and got shellacked in each of them.

"Watching Bannon make threats against entrenched Republican senators is like watching an armchair fantasy-football player manage a professional football team," National Journal political editor Josh Kraushaar writes. "He'll quickly find that beating Hillary Clinton may look like child's play compared to toppling entrenched Republican senators with ample resources behind them."

Or maybe not. Given the anger at the GOP "establishment," the Bannon-backed challengers might win their primary fights. Those candidates might then go on to lose in the general election, as McConnell recently warned in a Rose Garden appearance with the president. "Bannonism" -- to the extent that it's an "ism" -- may not appeal to the traditional conservatives and swing voters needed to win a general election.

If the Bannonistas lose, you can be sure Bannon will insist they were stabbed in the back by the "establishment" and "disloyal" Republicans. And if they win in the primaries or the general elections, it will certainly be due to their own merits and the anger of the GOP base at the Washington dysfunction that fuels right-wing populism these days. When it rains he'll dance, taking credit for wins he didn't earn, and he'll blame losses on the dysfunction he helps fuel.